Atlantic meridional nutrient transport 2004-2018 timeseries: insights into inorganic nutrient pool reorganization by the AMOC

North Atlantic (NA) biological productivity and resulting carbon uptake (Biological Carbon Pump, BCP) are supported by the northward transport of nutrients by the upper limb of the Atlantic Meridional Overturning Circulation (AMOC). Changes in the strength of the AMOC are subject to influence ocean nutrient cycling and the efficiency of the BCP. In this study, we present evidence for non-steady state behaviour based on 14 years of observations (2004-2018) at 26.5°N. Our results show significant (>80%) nutrient transport variability tightly related to AMOC alongside predominantly net southward nutrient transport exceeding total nutrient sources. Changes over the observational period indicate: i) increasing NA BCP efficiency (remineralized:preformed ratio); ii) decreasing NA nutrient inventory, except towards the end of the period when the system was closer to balance.